This story was written by CBS Radio News correspondent Cami McCormick for CBSNews.com.The Commandant of the U.S. Marine Corps says it's "high time" his troops leave Iraq and take their battle skills to Afghanistan.

"We are a fighting machine," Gen. James Conway tells CBS News, and the fight is now in Afghanistan.

On a whirlwind holiday visit to remote bases in Iraq and Afghanistan, Gen. Conway assessed the situation on the ground. He has made no secret of the fact he believes U.S. Marines would be better suited to the challenges in Afghanistan.

Their role in Iraq, he says, has been reduced to "nation building." In Anbar province, once the most dangerous province in Iraq, the violence has fallen to such low levels, Marines are working with the government on civil services.

"That's not what we do," Conway told Marines in Afghanistan. "Where there's a fight, that's where the Marine Corps is needed."

"If we track the number of foreign fighters into Iraq it's not nearly what it used to be," he said. "Similarly, there's a real up-tick of what we identify as foreign fighters in Pakistan moving over into Afghanistan. We're going to be here for a while."

At each "town hall" meeting at camps and bases decorated for the holidays, Conway told the Marines he expects a substantial buildup in Afghanistan in the months ahead, but only if there is a drawdown in Iraq.

"We're not going to try to do both. Whatever we send to Afghanistan must come as a result of a reduction in Iraq," he said. "When we come out of Iraq, we want to slam the door shut."

Listen to Cami McCormick's report from Afghanistan on troop levels Listen to Cami McCormick's extended interview with Gen. James Conway

There are currently more than 20,000 Marines in Iraq. And Conway would like to send as many as 10,000 to Afghanistan, where currently only a few thousand are on the ground.

Even if the deployment is approved in the coming weeks, a buildup of that magnitude would take months, and Conway is anxious to get started. His Marines are just as anxious. Many of them ask their commandant when they might be re-deployed.

Conway blames the resurgence of violence in Afghanistan on an "economy of force," partly due to the surge in Iraq. Roadside bombs doubled in 2008 from the previous year, according to the U.S. Ambassador to Afghanistan. Attacks against NATO forces are also on the rise. Violence has reached the highest levels since the invasion in 2001.

(CBS/Cami McCormick )

"There are pockets where they (the enemy) own ground and control villages where they will stand and fight. Up until this point, we have not had the force structure ... to do that," Conway said.

Conway finds himself caught between two senior U.S. commanders who both insist they need the Marines; Gen. David KcKiernan in Afghanistan and Gen. Ray Odierno in Iraq both see 2009 as a "critical year," according to Conway.

In Iraq, Marines are based along the western border with Syria, helping to stop the flow of foreign fighters into the important northern city of Mosul, still a flashpoint for al Qaeda in Iraq.

In Afghanistan, there is a resurgence of Taliban and other fighters battling British and Canadian forces, especially in the south where NATO bases are few and far between.

McKiernan wants the Marines to assist those NATO forces. Conway calls it a "conundrum," but he tells his troops there is a "newfound priority in Afghanistan."

And when President-elect Barack Obama's administration assumes power, he says, "that will help us greatly in determining where the forces need to go."

"It presents a unique dilemma of trying to determine, with only so much force in the barrel, who goes where." By Cami McCormick